Pen



FIG. 1 is an upper right perspective view of a pen showing my new design;

FIG. 2 is a right side elevation view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a front elevation view thereof;

FIG. 5 is a left side elevation view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a rear elevation view thereof.

The broken lines depicting the concentric circles in FIG. 3 illustrate environmental matter and form no part of the claimed design. The outer broken lines in FIG. 3 and the broken lines in FIG. 6 define the bounds of the claimed design and form no part thereof. 

The ornamental design for a pen, as shown and described. 